Radio receiving system



March 14, 1933.

A. s. RIGGS RADIO RECEIVING SYSTEM Original 'Filed March 2, 1927 2 Sheets-Sheet 1 March 14, 1933. A. s. RIGGS LQQLIZI RADIQ RECEIVING SYSTEM Original Filed March 2, 1927 2 Sheets-Sheet 2 INVENTOR Patented Mar. 14, i 1933 UNITED STATES PATIENT OFFICE,

ALGEB S. BIGGS, 0F NORTH IBERGEN TOWNSHIP, HUDSON COUNTY, NEW JERSEY RADIO nncnrvme' SYSTEM Application filed March 2, 1927, Serial No. 172,093. Renewed Kay 28, 1932.

comprising portions of the radio receiving set. A still further object of my invention is to provide restricted paths for the flow of the alternating currents generated in the amplifiers, and to restrict and confine these currents to their'correct respective portions of the circuit thus effectively eliminating conductive and other coupling between the circuits. -A

still further object of my invention is to provide a system ofoperation, including means of rectifying and filtering commercial alternating-current so that the radio receiving set is operated without the presence of excessive hum in the loud speaker, or other translating device, due to the frequency of the commercial supply line.

Referring to the drawings, of which Fig. 1 is a diagrammatic view of a radio receiving set comprising two stages of radio frequencyamplification, detector and two stages of audio frequency amplification together with such attendant apparatus and devices as are essential for the operation of the system constituting my present invention, and, Fig. 2 is a diagrammatic view of an audio frequency amplifier comprising two stages of transformer coupled audio amplification and the essential apparatus and devices to permit the operation of the amplifier from a commercial alternating current circuit. It is understood that portions of my invention are shown in the drawings merely for the purpose of illustration, and the drawings shall not be construed as a final and complete application of my present invention, inasmuch as the substitution of other apparatus and devices will not materially aifect the op-- eration of my system as a whole.

With reference to the drawings, and more the vacuum tubes V and V together with 6 attendant apparatus hereinafter described in greater detail.

The tuned transformer T is connected in conventional manner, ,thru grid condenser and leak to the vacuum tube V which functions as a rectifier, or more correctly, as a detector or de-modulator which resolves the modulated high frequency picked up from the antenna A into two major components:-a low or audio frequency, and a high or radio frequency. The output circuit of the tube V is so connected that the high frequency component of its output is short-cir cuited through the condenser C but the low,

or audio frequency, is amplified thru the transformer T tube V transformer T tube V and then is supplied to aloud speaker en translating device connected to the ter- 'minals12 of the audio amplifier of the apparatus. 1

It is evident by further inspection of the drawings that the filaments of the vacuum tubes, V V V and V are all connected in series, the negative end of such series being designated as point 3 which is connected to the negative side (4) of a filter system comprised by the inductance or choke coil L and the condensers Cn and C The positive end of this series of filaments, point 5, is

connected through resistance R to the point 6, which is the referred to. v

The filament of-tube V is supplied with current from the secondary S" of the transpositive side of the filter last former T a center tap of said secondary,

ments of V3, V1, V2, and V4 in the order named, thence to point 9 of the resistance R11. All of the current also flows through the portion of resistance R11 which is between points 9 and 8. Part of the current then flows through the resistance R11 above point 8 to the positive side of the filter at point 6, and part of the current flows through the tube V5 through the paths represented. by the filament to p1ate-resistance of V5,

thence through L12 to point 6.

Now, inasmuch as the plate current to the tube V5 flows through a choke, or inductance, L12, it is evident that this circuit is one of high reactance and is therefore a direct current branch circuit. Hence the normal current taken for the plate of tube V5 (which is usually a power tube requiring large directcurrent and voltage) is also used for partly maintaining the filament heating current of the tubes V1, V2, V3 and V4.

The maximum current taken from the filter system is therefore equal only to the filament current of a tube similar to V1, V2, V3

or V4, plus the space currents taken by these tubes under normal conditions.

By further inspection of the drawings it will be seen that the resistances R1, R2, R3, and R4 are connected across the filaments of tubes V1, V2, V3 and V4, respectively, these resistances being of such values as to efiectively by-pass that portion of the total current taken from the filter system which is not required to heat the filaments of V1, V2, V3 and V4.

From the foregoing, it will be seen that the cireuit'including the filaments of tubes V1, V2, V3 and V4 comprise a portion of a direct current series circuit which includes the resistance R11 and the direct-current plate resistance of tube V5.

Now, in a vacuum tube circuit there are two currents present: one being a direct-current, and the other being an alternating-current component super-imposed thereon. My system contemplates the proper separation and restriction of both these components to proper paths. This separation effectively restricts the alternating-currents .to a well-defined path which is as follows :-From plate (or anode) and filament of the tube, between which the alternating-current component is generated, to and through the transformer, or other electro-responsive device and the plate circuit of the tube, thereby insuring the presence of direct-current only in the circuit opposition to the flow of said components than does the path through the resistance B5.

In each of the amplifier circuits 1 have provided filter systems consisting of suitable bypass condensers and resistances which function as above described.

It is seen that the grids of all tubes are maintained at proper predetermined potentials, the filaments of tubes V1, V2, V3, and V4 being so located in the circuit as to allow all grid return leads to be brought to a common point.

Resistance capacity filters are provided in the grid returns of all audio stages for the purpose of eliminating coupling and also to obviate the possibility of an alternating-eurrent component originating in the main filter (L1, C11 and C12) from being passed on to the grids of the amplifier tubes.

The power supply consists of a power transformer, T5, having a primar winding, P, which is energized from an a ternatingcurrent circuit through the ballast resistance R13, which in combination with the resistance R12 acts to maintain a constant voltage across the terminals of the primary P of the power transformer T5. The secondary S serves to furnish power for heating the filaments or cathode of the rectifier tubes, V6 and V7. The secondary windings S serves to furnish high potential for the rectifier; and the winding S serves to supply cnrrent to the filament or cathode of the power tube V5.

The rectified current passes into the radio vrent from the rectifier system to a su stantially pure direct-current. The condenser C13 is placed in the-circuit for the purpose of by-passing alternating-current components which would otherwise travel through the series circuit containing the filaments of tubes V1, V2, V3, and V4.

From the foregoing it is evident that the system comprising my'present invention represents a stable circuit having a constant current direct-current branch, and several wellrestricted alternating-current paths for the fiow of currents of corresponding qualities.

In Fig. 2 of the drawings I have shown more particularly the circuit connections for the power supply stages of the radio receiver where a power amplifier is constituted by audio frequency transformer systems T1 and T2 which rovide the coupling means for the circuits oi the electron tubes. The power transformer and rectification system are shown arranged in the same-manner as in Fig. 1. The rectifier tubes are indicated at V3 andV4 for full wave rectification of the alternating current power supply. The filter circuit is constituted bycondensers C5 and C6 and inductive reactance L2 and the input circuit thereof connected to the cathode circuit of electron tube V1 and to the output circuits of each of the electron tubes. I have illustrated the circuit connections for the output circuit of electron tube V1 as extending from a tap on resistance R4 through filter resistance R1. The output circuit of electron tube V2 is completed through the choke or inductance L1 connected to the positive side of the filter circuit. The biasing potential for each of the power amplifier stages is supplied from the negative side of the filter circuit through resistance R2 and from a tap on resistance R3 through the resistance R to the grid circuit of electron tube V1. I provide blocking condensers C1, C2,

. C3 and C7 disposed in the input and output circuits of the power amplifier stages for preventing the interference of hum from the supply system in the circuits of the electron "30 tubes.

I also provide a condenser C4 in the sound reproduced circuit for the further reduction of interference from noises inherent in thesupply circuit. The condensers C1, C2, C3, C7 and C4 serve to restrict andseparate the paths of the alternating and direct current components. It will be observed that the cathode of electron tube V2 is energized from the secondary winding S" of the power transformer system while the cathode of electron "tube V1 is excited from a direct current derived from the rectification system. The cathode circuit for electron tube Vlis completed through the midtap of secondary winding S" and the anode'circuit of electron tube V2. h It is therefore evident that the space current of the electron tube V2 passes through the cathode of electron tube V1 there by supplying a portion of the power necessary to maintain the last mentioned cathode at proper temperature. It is therefore evident that this results in a considerable saving of power drawn from the rectification part of the system.

It is understood that modifications and changes may Be made in my system without departing from the spirit of the original invention or the scope of the appended claims.

, Iclaim:

1. A radio receiving system including a plurality of electron tubes connected in cascade, an alternating current power source, a rectification circuit for supplying rectified current to the circuits-of said electron tubes, a distribution circuit connected with said rectificationcircuitand inde ndentreactance devices interposed in series etween points in each of the output circuits of said electron plurality of electron tubes, a power source of alternating current, a rectification system, v

means for supplying constant current from said rectification system to the circuits of said electron tubes, a power distribution circuit connected in shunt with said rectification system and a reactance constituted in part, by a resistance interposed in series in each of the leads between the output circuits of the several tubes and the input circuits of selected tubes and said power distribution circuit for energizing the output circuits of said electron tubes while preventing interference from the alternating current source.

3. A radio receiving system including a plurality of electron tubes connected in cas-.

c-ade, a' power source of alternating current, a rectification system for supplying rectified current to the circuits of said electron tubes, a power distribution circuit connected with said rectification system, a capacity reactanceinterposed in series between a point in each of the output circuits of said electron tubes and the cathodes thereof, individual reactance members connected between the said points in said output circuits and one side of the power distribution circuit connected with said rectification system and separate reactance members connected between the input circuit of selected tubes and said system for energizing the circuits of said electron tubes while preventing interference from said alte nating current source.

4. A radio receiving apparatus including a plurality of electron tubes connected in casc'ade, a power source of alternating current,

arectification system, circuits for delivering constant current from said rectification system to the circuits of said electron tubes, resistance members interposed in series between one side of said first mentioned circuits and points in each of the output circuits of said electron tubes for impressing high potentials upon the output circuits of said electron tubes while preventing interference in said electron,

tube circuits from said alternating current source and separate resistance members connected between said system and the input circuits of selected electron tubes.

5. In a radio receiving system the combination with a plurality of electron tubes connected in cascade, a source of alternating current power, a rectification system, a filter associated. therewith, connections whereby said electron tubes are energized from said rectification system, means for preventing inter-stage coupling between said electron tubes including resistances interposed in series between said filter circuit and the output circuits of each of said electron tubes,

and capacitive reactances interposed in series between the cathodes of said electron tubes, the output circuits of said electron tubes and the last mentionedresistances for restricting and confining alternating and direct current components to independent paths in said circuits and separate resistance members connected between said system and theinput-circuits of selected electron tubes.

6. In a radio receiving system including a plurality of electron tubes, input and output circuits coupling said tubes, a power source of alternating current, a rectification system, a filter circuit for delivering constant current to the circuits of said electron tubes, connections between the output circuits of said electron tubes and said filter circuit, and connections between selected ones of the input circuits of said electron tubes and said filter circuits and condensers connected in shunt between said connections and the cathode circuits of the several. electron tubes, said connections including in series position resistance members independent one from an other for controlling the potential impressed upon said circuits while preventing interference from the power source of alternating current.

7. In a radio receiving system including a plurality of electron tubes each having input and output circuits coupled one to the other, a rectification system interposed between a power source of alternating current and the c1rcu1ts of said electron tubes, the

output circuits of selected electron tubes hav- I ing resistance members interposed in series between said rectification system and the input circuits of selected ones of said tubes having independent reactances interposed in series with said rectification system, and auxiliary reactances connected between said first mentioned resistance members and the oath ode circuits of said tubes for confining the alternating and direct current components to separate paths andpreventing interference from the alternating current source in said electron tube circuits.

8. A radio receiving system including a.

plurality of electron tubes arranged in cascade, input and output circuits for each of said tubes, a power source of alternating current, a rectification system, means interp osed between said source and said rectification system for eflecting the delivery of constant current to the circuits of said electron tubes,

a cathode circuit including'the cathodes of selected onesof said electron tubes in series, connections between said cathode circuit and said rectification system, and resistance members'interp'psed between each cathode in plurality of electron tubes each having input and output circuits and having their cathodes arranged in series relation, an alternating current power supply for said tubes, the order of arrangement of said cathodes being such that all grid returns of saidelectron tubes may be grouped and brought to a common point thereby maintaining selected predetermined potentials on each of the grids of the several electron tubes composing a part of said system and resistors in series with each of the output circuits of said tubes and said source. 1

10. In a radio receiving system including a plurality of electron tubes having input and output circuits and having their cathodes arranged in 'series relation including a source of rectified and filtered alternating current for energizing said cathodes and for supplying potentials to the input and output circuits of said electrontubes, a circuit connecting all grid returns in said system to a common point with respect to said source, separate alternating current and direct current branches connected with said cathodes and isolated by capacitive reactance and resistance on one side of each ofsaid cathodes and capacitive reactance on the other side of each of said cathodes and resistors in series with each of the output circuits-of said tubes and said source.

11. A radio receiving system including a plurality of electron tubes constituting amplification of detector stages each having input and output circuits, means coupling'the output circuit of one electron tube with the input circuit of a succeeding electron tube, a ower'source of alternating current, a recti cation and filter power distribution sys tem interposed between said power source and said electron tube circuits, connections including resistances connecting in series between said power distribution system and points in the input and output circuits of said detector stage and selected amplification stages, and condensers disposed between the ends of said resistances and the cathode elements of said tubes, for separating the alternating and direct current components in said circuits and preventing interference from said source.

ALGER S. RIGGS. 

